john v



(No Model.)

J. V. GAPEK. ELECTRICAL HEATER.

No. 449,036. Patented Mar. 24, 1891.

@29th/mo UNITED STATES PATENT OEEICE.

JOHN V. .lA'PElL OF EW YORK, N. Y., ASSIGOR OF ONEdlAlrl" TO EDVARD H. JOHNSON, OF SAME PLACE.

ELECTRICAL H EATR.

SPECIFICATION forming part of Letters Patent No. 449,036, dated March 24, 1891.

Application filed July 2l, 1890. Serial No.. 359,397. (No model.)

T all whom it may concern:

Be it known that I, JOHN Y. OAPEK, a citizen of the United States, residing at New York city, in the county. and State of New York,

have invented a certain new and useful lmproveinent in Electrical lleaters, of wh ich the following is a specification.

ln the accompanying drawings, which illustrate my invention, Figure l is a plan view of i0 a heating-strip. 2 is an inverted plan of a part of said strip. Fig. 3 is a side view thereof. Fig. et is a plan view of several strips grouped on a suitable base, and Fig. 5 is a sectional view of a heater supported on a platform and covered by a lid.

lt is sometimes desirable in cooking (as when the material to be cooked covers a coinpara-tively large surface-for example, the bottoni of the pan) to have the heat also diffused over a correspondingly large surface under the pan. Moreover, the heating-conductor should be so arranged that the largest possible percentage of the heat generated should be effective. This is not the case with a heating-Wire which is round in cross-section, since the heat rays diverge in all directions, and only those which extend vertically upward fall directly on the vessel to be heated. Hence with such a Wire the effective radiating capacity is in evident inisproportion with the conduc-tingcapaeity of the heating-conduetor, and to obtain a given temperature it is necessary to use a large conductorto avoid overheating and consequent fusion. The present invention is believed to fulfill the requirements in this class of heaters.

I take a strip of foil of German silver (say .O02 inches thick) or other suitable high-resistance conductor, preferably about two inches Wide, and eut slits of about one-sixteenth inch alternately from opposite edges, thereby forming a zigzag strip, as indicated at l, although it is not essential that the conductor be formed of one integral sheet, as above set forth. The resistance of this conductor may be varied indefinitely by varying the Width of the slits cut in the sheet. The conductor is placed on one surface of a strip 2 of asbestus, porcelain, mica, or other suitable heat-resisting insulating material, and may be attached in any desirable manner.

lt is preferable, however, to make strip 2 narrower than the strip Vfrom which the zigzag conductor is formed, and then to bend the edges of the metal strip over the edges of strip 2, as clearly shown at 3, Figs. 2 and 3 of the drawings. A conductor thus arranged possesses the greatest possible radiating-surface and renders it unnecessary to increase its size in order to obtain suliicient conductivity for the production of a definite temperature, as indicated above in connection with ronnd- Wire conductors.

To further guard against the effect of high temperature on the conductor, the foil is covered by an electroplating of another metal. This may be a metal which readily oxidizes, such as iron or copper, or it may be a metal not readily oxidzable, such as nickel or platinuin. A thin coating of either of'these niet als will not'decrease the electrical resistance in as great a ratio as it increases the fusingpoint of the conductor as a whole. It Will therefore protect and strengthen thc foil.

When strip l has been placed on an insulating-strip, a circuit-wire is connected to either end. The Wire may be Wound around the compound strip, as shown in Figs. l and 3, or may be connected in any other suitable manner. A second strip of asbestus or other material l is placed against the under surface of strip 2 and the turned edges S of the conductor, and strips 2 l are fastened` together by any suitable ineans.

Several of the prepared strips may be placed in separate groups on a com mon base preferably of hardened asbestus or a multiple sheet of asbestus, the top and bottoni layers being hardened. Over the strips thus arranged may be placed a metal frame or grate 6 (say from one-eighth to one-fourth inch in thickness) with or Without the cross-bars 6. This grate may or may not forni the only means for securing the strips on the base. The metal grate being in intimate relation With the heater serves to diffuse the heat, and since the metal bottom of the cooking-vessel is placed directly thereon it may be considered as a metallic extension of said vessel, serving to form an uneven bottom of large surface and to bring the same nearer to the heater and at the saine time preventing injury of the IOO of bolts. The perforations in frame G shouldv be so large that there Will be no metal contact between said frame and the bolts. This is necessary to prevent conduction of heat away from the upper surface of the heater.

The circuit is ordinarily connected in se ries through all the strips; but this form of connection is not essential. The circuit-wires 7 may pass through the base and be united into a cord, the wires being insulated lfrom cach other and terminatingin a suitable connecting device.

With a fiat conductor mounted on an insulating-strip there is practically no danger of short-circuiting between the several parallel turns of the conductor, since the whole conductor rests on the supporting-strip and will not be readily displaced, and expansion due to changes in temperature of the conductor could not sufficiently distort the same to bring the turns together. The operation of the above-described apparatus has been sufficiently indicated by the description ot' the apparatus itself and need not be repeated.

In Fig. 5 the heater is shown placed on a table or other platform 8. A pan 9 rests on the heater, and a cover l10 is over the pan and heater. No oven of special construction is necessary.

WVithout confining myself to all the details of construction above set forth, what I claim 1s 1. In an electrical heater, the combination of a strip of heat-resisting insulating material and a iiat zigzag heating-conductor on one face of said strip, substantially as described.

2. In an electrical heater, the combination of a strip of heat-resisting insulating material and a flat zigzag heating-conductor on one face of said strip and bentover the edges there- 0f, whereby it is held in place, substantially as set forth.

3. In an electrical heater, the combination of a strip of heat-resisting insulating material and a fiat zigzag heating-conductor on one face of said strip and a re-enforcing strlp of yheat-resisting material upon the second face as described.

6. In an electrical heater, the combination,

. With a base, of heating-conductors thereon, a

metal grate placed over the same, and the ex'- tended and insulated circuit-wires, substantially as described. 7. In an electrical heater, the combination, with a base, of heating-conductors thereon, a metal grate'placedover the same, and a metal frame under the same, the several parts being connected together and the lower frame being insulated from .the grate, substantially as described.

`8. An electrical heater-conductor of German silver or other suitable metal covered with an electroplating of different metal, substantially as described.

9. A conductor for electrical'heaters, consisting of a thin sheet of foil slitted alternately from opposite edges, Wherebya zigzag conductor is produced, substantially as described.

10. A conductor for electrical heaters, consisting of a thin sheet of foil slitted alternately from opposite edges and covered with a layer of a different metal, substantially as described.

This specification signed and witnessed thisv CHARLESY M. CATLIN, SEIBERT SoHUcK. 

